Phoenix, Arizona


Pai.Rish@mayo.edu Clinical Profile


Rish K. Pai, M.D., Ph.D., has an active research interest in the histopathology of inflammatory diseases of the gastrointestinal (GI) tract and liver. Dr. Pai is particularly interested in the role of histologic disease activity measurements in predicting clinical outcomes and response to treatment. He is involved in developing validated and responsive scoring systems for measuring disease activity.

Dr. Pai is also interested in molecular and morphologic aspects of colorectal carcinoma. In particular, he has focused his research on microsatellite unstable colorectal carcinomas in both sporadic and hereditary forms. He has a general interest in the pathologic aspects of colorectal carcinoma that affect treatment and prognosis. Using deep learning tools to better evaluate colorectal carcinoma specimens is another area of keen interest. Dr. Pai is also the principal investigator for the Colon Cancer Family Registry at Mayo Clinic, a branch of the Colon Cancer Family Registry (Colon CFR) Cohort. The Colon CFR Cohort is an international consortium of six institutes in the U.S., Canada and Australasia formed as a resource to support studies on the etiology, prevention and clinical management of colorectal cancer.

Focus areas

  • Histologic scoring systems. With the emergence of new therapies to treat inflammatory diseases of the GI tract and liver, there is a need to develop validated and responsive instruments to determine treatment efficacy. Improved instruments to measure disease activity will result in improved clinical trial design and facilitate development of effective therapies. Dr. Pai uses histologic scoring systems to better evaluate treatment response in inflammatory diseases of the GI tract and liver, including inflammatory bowel disease, eosinophilic esophagitis, nonalcoholic fatty liver disease and celiac disease.
  • Pathologic features of colorectal carcinoma. Colorectal carcinoma continues to be a leading cause of cancer-related deaths despite improvements in screening and therapies. Pathology plays a key role in providing important prognostic information as well as helping guide appropriate chemotherapy. Improved identification and quantification of key pathologic features that are important in predicting prognosis and therapeutic response would result in improved outcomes for patients with colorectal carcinoma. Dr. Pai strives to identify key pathologic features in colorectal carcinoma that predict survival, response to therapy and underlying molecular alterations.

Significance to patient care

Dr. Pai's research on developing validated and responsive indices for inflammatory diseases of the gastrointestinal tract and liver will result in improved outcome measures for routine clinical use, as well as for clinical trials. In addition, improved pathologic evaluation of colorectal carcinoma will lead to improved patient outcomes.

Professional highlights

  • Member, Editorial board, American Journal of Surgical Pathology, 2014-present
  • President, Rodger C. Haggitt Gastrointestinal Pathology Society, 2020-2021
  • Member, Education Committee, United States and Canadian Academy of Pathology, 2017-2020
  • Recipient, Jack Yardley Investigator Award, Rodger C. Haggitt Gastrointestinal Pathology Society, 2019


See my publications


Primary Appointment

  1. Consultant, Department of Laboratory Medicine and Pathology

Academic Rank

  1. Professor of Laboratory Medicine And Pathology


  1. Fellow - Gastrointestinal and Hepatic Pathology The University of Chicago Medical Center
  2. Chief Resident - Anatomic Pathology The University of Chicago Medical Center
  3. Resident - Anatomic Pathology The University of Chicago Medical Center
  4. MD/PhD - Immunology Case Western Reserve University
  5. BA - Chemistry Pomona College

Mayo Clinic Footer